JP2021503052A - Pressure control of independent gas containing system in multiple coal seams Single pump mining equipment and mining method - Google Patents

Abstract

The present invention discloses a controlled pressure single pump mining apparatus and mining method for an independent gas containing system in multiple coal seams. The device includes an inner mantle tube and an outer mantle tube, an oil supply pipe is provided inside the inner mantle tube, a soccer rod is provided inside the oil supply pipe, and a bottom end portion of the soccer rod and a tube pump are provided. Connected, a sand-sinking pipe is provided at the bottom of the tube pump, a sieve pipe is provided above the sand-sinking pipe, and a first packer and a second packer are provided between the inner pipe and the outer pipe. The inner tube wall of the inner tube is provided with a pressure gauge electric pump and an annular current limiting valve electric pump, the bottom end of the pressure gauge electric pump is connected to the pressure gauge, and the pressure gauge is the bottom of the inner wall of the inner tube. Provided at the end, the bottom end of the annular current limiting valve electric pump is connected to the annular current limiting valve of each independent gas containing system. An annular current limiting valve is attached to the present invention to control the amount of water flowing into the pump port of the inner mantle. The dynamic liquid level auxiliary pipe partitions the gas produced by each independent gas-containing system, and a gas flow meter is attached to the apex of the dynamic liquid level auxiliary pipe to observe the gas output of each gas-containing system. it can.

Description

The present invention relates to the technical field of coal mine development, and more particularly to a controlled pressure single pump mining apparatus and mining method for an independent gas containing system in a plurality of coal mines.

When performing coal seam gas mining in multiple coal seams, different gas content systems are affected by factors such as reservoir heterogeneity, reservoir pressure, liquid supply capacity, permeability, coal seam gas content and gas saturation. Interlayer interference phenomenon often appears between them, which may reduce the production capacity of the gas well. Those skilled in the art have conducted a lot of research on basic geology, crushing and drainage, mining, etc. related to coal gas, but the research is mainly on a single coal layer, and prior research on a system containing multiple coal layers independent gas. Is almost nonexistent. Currently, the production capacity of gas wells in several coal seams area is low, and the equipment, method and technology of "stratified pressure control, layer composite mining" proposed in the prior art can separate each coal seam in the vertical direction, but each coal seam. It is difficult to optimize mining in the mining process because the rate of drainage and step-down cannot be controlled and the gas production capacity of each coal seam cannot be monitored.

In order to solve the above-mentioned drawbacks of the prior art, the present invention provides a controlled pressure single pump mining device and a mining method for an independent gas containing system in a plurality of coal seams. According to the present invention, an independent dynamic liquid level is formed in each independent gas-containing system, and the drainage / depressurization rate of each independent gas-containing system is adjusted based on the result of the numerical simulation calculated in the previous period. Interlayer interference is reduced, pressure drop distribution (PRESSURE DROP FUNNEL, pressure drown distribution) is as widespread as possible, increasing gas production.

The present invention proposes the following technical solutions.

A control pressure single pump mining device for an independent gas-containing system in multiple coal seams, comprising an inner stalk and a stalk, the stalk is fitted outside the stalk, and the stalk is plural. An oil feed pipe is provided inside the inner body pipe, a soccer rod is provided inside the oil feed pipe, and a bottom end portion of the soccer rod and a tube pump are connected to penetrate the independent gas-containing system. A sand-sinking pipe is provided at the bottom of the pump, a sieve pipe is provided above the sand-sinking pipe, a first packer and a second packer are provided between the inner and outer mantle tubes, and the first packer is provided. Is provided on the outside of the inner mantle corresponding to the bottom end of each independent gas containing system except the bottom two independent gas containing systems, the second packer being the second from bottom to top. Provided on the outside of the inner tube corresponding to the bottom end of the independent gas-containing system, the inner tube wall of the inner tube is provided with a pressure gauge electric wire and an annular current limiting valve electric wire, and the bottom end portion of the pressure gauge electric wire. Is connected to a pressure gauge, the pressure gauge is provided at the bottom end of the inner wall of the inner wall, and the bottom end of the annular current limiting valve is connected to the annular current limiting valve of each independent gas containing system. Provides a controlled pressure single pump mining device for independent gas containing systems in multiple coal seams.

Further, the outer wall of the inner mantle is provided with a plurality of semi-annular openings, and an annular current limiting valve is attached to the outside of the semi-annular opening, and the height and diameter of the annular current limiting valve are the height of the semi-annular opening. And to provide a controlled pressure single pump mining device for independent gas containing systems in multiple coal seams larger than the diameter.

Further, the annular current limiting valve is composed of a current limiting valve and a tractor, the opening size of the annular current limiting valve is controlled by pulling in the tractor on the current limiting valve side, and the annular current limiting valve electric pump is an inner tube. Provided is a controlled pressure single pump mining device for an independent gas containing system in multiple coal seams that penetrates a wall and is connected to a tractor.

Further, the mining device includes a gas flow meter for measuring the gas production of the independent gas-containing system and a centralizer for fixing the inner pipe, and the gas flow meter is fixed at the wellhead. The centralizer provides a controlled pressure single pump mining device for an independent gas containing system in multiple coal seams, which is provided between the inner and outer pipes.

Further, a gas production auxiliary passage and an inner casing passage are provided in the longitudinal direction of the first packer, and the inner trouser passage is located in the central portion of the first packer, and the gas production auxiliary passage and the inner trousers are provided. The passage is externally contacted, and the diameter of the gas production auxiliary passage is smaller than that of the inner casing passage, the inner trousers penetrate the inner trouser passage and are fixed to the cloak, and the second packer is at the bottom end. Independent gas-containing system and the independent gas-containing system at the bottom end and the adjacent independent gas-containing system are partitioned so that each independent gas-containing system has an individual independent structure and in the longitudinal direction of the second packer. Provided is a controlled pressure single pump mining device for an independent gas containing system in multiple coal seams, provided with an inner pipe passage for penetrating the inner pipe.

Further, the mining device includes a plurality of gas production auxiliary pipes, the gas production auxiliary pipe penetrates the gas production auxiliary passage, and the gas production auxiliary pipe, the upper end portion and the gas flow meter are connected, and the lower end portion is , Each of which is communicated with the corresponding independent gas-containing system, the gas production auxiliary pipe is used for observing and adjusting the dynamic liquid level of each independent gas-containing system, and the control pressure of the independent gas-containing system in multiple coal seams is simple. (1) Provide a pump mining device.

Further, the lower end of the gas production auxiliary pipe is an independent gas-containing system in a plurality of coal seams which communicates with each independent gas-containing system excluding the independent gas-containing system at the top end and the independent gas-containing system at the bottom end. A controlled pressure single pump mining device is provided.

Control pressure of independent gas-containing system in multiple coal seams A single pump mining method based on the principle of permeation dynamics and by linking coal seam gas development experiments and numerical simulation technology to predict the transmission pattern of coal reservoir pressure. The coal seams in the target area are partitioned into three independent gas-containing systems based on the steps used as the basis for the emission of the annular current limiting valve and the single coal seam gas content characteristics in the target area and the layer distribution characteristics of the reservoir pressure. Then, according to the partitioned independent gas-containing system, the first packer is attached to the outside of the inner pressure tube at the bottom end of the first independent gas-containing system, and the inner pressure tube at the bottom end of the second independent gas-containing system. A second packer is attached to the outside, the gas production auxiliary passage in the first packer and the gas production auxiliary pipe are communicated with each other, the pressure gauge electric wire and the pressure gauge are connected, and the pressure gauge is attached to the bottom of the inner wall of the inner wall. After being fixed, the step of sealing the part connecting the pressure gauge, the pressure gauge and the pressure gauge electric wire, the partition result of the independent gas-containing system, and the reservoir characteristics of each gas-containing system are used as the result of the numerical simulation. When the maximum gas production capacity of each independent gas-containing system is reached, a semi-annular opening is opened according to the height of the liquid column, and a stress receiving portion is installed in advance, and an annular limit is provided outside the semi-annular opening. A flow valve is installed, where two annular current limiting valves are installed, an annular current limiting valve electric wire penetrates the tube wall of the inner mantle and is connected to the annular current limiting valve tractor, and finally with the annular current limiting valve. The step of sealing the connection part with the annular current limiting valve electric wire, and the inner mantle, packer, and gas production auxiliary pipe that fix the annular current limiting valve and the pressure gauge are fixed at the design depth, and the packer is sealed and inside. A step where an independent space corresponding to the independent gas-containing system is formed between the mantle and the mantle, and a wellhead is installed to start pumping and during mining, a reservoir of three independent gas-containing systems. Based on the characteristics and the results of numerical simulation, the amount of drainage of the annular current limiting valve is planned, the opening size of each annular current limiting valve is controlled, and the amount of water flowing into the pump port of each independent gas containing system is controlled. While reading the pressure gauge and gas flowmeter readings, make sure that the pressure gauge readings are steadily decreasing, reduce damage to the reservoir, spread the pressure drop distribution as much as possible, and gas flowmeter readings. And the step as a reference for adjusting the flow rate of the annular current limiting valve by comparing the result of the numerical simulation or based on the reversal calculation.
In the later stages of mining, the dynamic liquid level is reduced after the liquid production of the coal seam is reduced, the stroke is reduced, the rate of descent of the dynamic liquid level is reduced, and the maximum gas production capacity is reached for each independent gas-containing system. Provided is a controlled pressure single pump mining method for an independent gas containing system in multiple coal seams, including a step down to the top boundary of a semi-annular opening so that the coal seams are not exposed.

Compared with the prior art, the present invention has the following advantages.

(1) The coal layer group is divided into different gas-containing systems and packed into packers for each independent gas-containing system according to the difference in the characteristics of the coal reservoir, and the different gas-containing systems are sealed by different pressure systems. .. In addition, the inner tube is provided with a semi-annular opening at a specific position corresponding to the independent gas-containing system, and an annular current limiting valve is attached. By adjusting the opening and closing of the valve, the amount of water flowing into the pump port of the inner shell can be controlled, the pressure drop distribution of each independent gas-containing system is widened, and the production capacity of each independent gas-containing system is increased. can do.

(2) The gas production auxiliary pipe separates the gas generated in each independent gas-containing system, and a gas flow meter is attached to the top end of the gas production auxiliary pipe, and the amount of gas produced in each independent gas-containing system. Can be measured, and the flow rate of the annular current limiting valve is modified by comparing the predicted result obtained by numerical simulation with the actual gas output or based on the reversal calculation, and the pressure drop distribution of each independent gas-containing system. The spread of gas can be maintained stably.

It is a conceptual diagram which shows the structure of the control pressure single pump mining apparatus of the independent gas containing system in the plurality of coal seams of this invention. It is a conceptual diagram which shows the structure of the annular current limiting valve of this invention. FIG. 3a is a cross-sectional view of the first packer, and FIG. 3b is a cross-sectional view of the second packer.

1: Pressure gauge electric pump, 2: Circular current limiting valve electric cord, 3: Gas flow meter, 4: Centralizer, 5: Soccer rod, 6: Oil supply pipe, 7: Manometer pipe, 8: Manometer pipe, 9: Ring limit Flow valve, 10: Gas production auxiliary pipe, 11: 1st packer, 12: 2nd packer, 13: Tube pump, 14: Sieve tube, 15: Sand sedimentation pipe, 16: Pressure gauge, 17: Current limiting Valve, 18: tractor, 19: gas production auxiliary passage, 20: manometer passage.

In order to better understand the present invention, the present invention will be described with reference to the following drawings and embodiments. The following embodiments are for understanding the present invention and do not limit the scope of protection of the present invention.

As shown in FIGS. 1 and 2, a control pressure single pump mining device for an independent gas-containing system in a plurality of coal seams includes an inner mantle tube 8 and an outer mantle tube 7, and the inner mantle tube 8 is the mantle tube 7. Provided internally (i.e., the mantle tube 7 is fitted outside the mantle tube 8), the mantle tube 7 penetrates a plurality of independent gas-containing systems and is inside the mantle tube 8. , The oil supply pipe 6 is provided, the soccer rod 5 is provided inside the oil supply pipe 6, the bottom end of the soccer rod 5 is connected to the tube pump 13, and the sand sink pipe 15 is provided at the bottom of the tube pump 13. , A sieve pipe 14 is provided above the sand sink pipe 15.

A first packer 11 and a second packer 12 are provided between the inner mantle tube 8 and the mantle tube 7, and the first packer 11 is independent except for the two independent gas-containing systems on the lowermost side. Provided on the outside of the inner trousers 8 corresponding to the bottom end of the gas containing system, the second first packer 2 corresponds to the bottom end of the second independent gas containing system from bottom to top. It is provided on the outside of the casing 8.

The inner tube wall of the manometer 8 is provided with a pressure gauge electric wire 1 and an annular current limiting valve electric wire 2, the bottom end of the pressure gauge electric wire 1 is connected to the pressure gauge 16, and the pressure gauge 16 is inside. It is fixed to the bottom end of the inner wall of the manometer 8, and the bottom end of the annular current limiting valve electric wire 2 is connected to the annular current limiting valve 9 of each independent gas containing system.

In the above embodiment, the outer wall of the inner mantle tube 8 is provided with a plurality of semi-annular openings, and an annular current limiting valve 9 is attached to the outside of the semi-annular opening, and the height and diameter of the annular current limiting valve 9 are different. Greater than the height and diameter of the hemispherical opening. The annular current limiting valve 9 is composed of a current limiting valve 17 and a tractor 18, and the opening size of the annular current limiting valve 9 is controlled by the pulling operation of the tractor 18 on the current limiting valve 17 side, and the annular current limiting valve electric wire is used. 2 penetrates the wall of the inner mantle 8 and is connected to the tractor 18.

In the above embodiment, the mining apparatus includes a gas flow meter 3 for measuring the gas production from the independent gas-containing system and a centralizer 4 for fixing the introductory pipe, and the gas flow meter 3 is , The centralizer 4 is provided between the inner pipe 8 and the outer pipe 7, the gas flow meter 3 is a spiral flow meter (Swirlmeter / vortex measurement flowmeter), and the centralizer 4 is It is an elastic displacement regulation centralizer.

As shown in FIG. 3, in the longitudinal direction of the first packer 11, a gas production auxiliary passage 19 and an inner casing passage 20 are provided, and the inner casing passage 20 is located at the center of the first packer 11. The gas production auxiliary passage 19 and the inner casing passage 20 are externally located, and the diameter of the gas production gas production auxiliary passage 19 is smaller than that of the inner casing passage 20, and the inner casing 8 is the inner casing passage. It penetrates 20 and is fixed to the mantle tube 7. The second first packer 2 partitions the independent gas-containing system at the bottom end and the independent gas-containing system adjacent thereto, and each independent gas-containing system has an individual independent structure, and the length of the second first packer 2 is long. In the direction, the inner mantle passage 20 for penetrating the inner mantle 8 is provided.

In the above embodiment, the mining apparatus includes a plurality of gas-producing gas-producing auxiliary pipes 10, the gas-producing gas-producing auxiliary pipe 10 penetrates the gas-producing gas-producing auxiliary passage 19, and the upper end of the gas-producing auxiliary pipe 10. The unit and the gas flow meter 3 are connected, and the lower end is communicated with the corresponding independent gas-containing system, and the gas production auxiliary pipe 10 is used for observing and adjusting the dynamic liquid level of each independent gas-containing system. Can also be used.

Hereinafter, the steps to be carried out will be described by taking as an example the mining of a coal seam gas system of three independent gas-containing systems with a controlled pressure single pump.

(Step 1)
Based on the principle of permeation mechanics (fluid mechanics in porous medium, Mechanics of Fluids in Porous Media), and in combination with coal seam gas development experiment and numerical simulation technology, predict the transmission pattern of coal reservoir pressure, and ring current limiting valve. It is used as a standard for the amount of emissions.

(Step 2)
Based on the single coal layer gas content characteristic of the target region and the layer distribution property of the reservoir pressure, the coal seam group of the target region is partitioned into three independent gas containing systems, and the first independent according to the partitioned independent gas containing system. A first packer is attached to the outside of the manometer at the bottom end of the gas-containing system, a second packer is attached to the outside of the manometer at the bottom end of the second independent gas-containing system, and the gas in the first packer. After connecting the production auxiliary passage and the gas production auxiliary pipe, connecting the pressure gauge electric wire and the pressure gauge, and fixing the pressure gauge to the bottom of the inner wall of the manometer, the pressure gauge, the pressure gauge and the pressure gauge. Seal the part that connects to the electric gas.

(Step 3)
Based on the partition results of the independent gas-containing systems and the reservoir characteristics of each gas-containing system, linked to the results of numerical simulations, depending on the height of the liquid column at the time of reaching the maximum gas production capacity of each independent gas-containing system. A semi-annular opening is opened and a stress receiving part is installed in advance, and an annular current limiting valve is attached to the outside of the semi-annular opening. Here, two annular current limiting valves are installed, and an annular current limiting valve electric wire is installed. It is connected to the annular current limiting valve tractor through the pipe wall of the pipe, and finally, the connection portion between the annular current limiting valve and the annular current limiting valve electric wire is sealed.

(Step 4)
Fix the manometer, packer, and gas production auxiliary pipe that fix the annular current limiting valve and the pressure gauge to the design depth, seal the packer, and create an independent gas-containing system between the manometer and the manometer. A corresponding independent space is formed.

(Step 5)
Install the wellhead, start pumping, and during mining, plan the drainage volume of the annular current limiting valve based on the reservoir characteristics of the three independent gas-containing systems and the results of numerical simulations, and for each annular current limiting valve. By controlling the opening size, controlling the amount of water flowing into the pump port of each independent gas-containing system, and reading the measured values of the pressure gauge and gas flow meter, confirm that the value of the pressure gauge is surely reduced. Adjust the flow rate of the annular current limiting valve by comparing the gas flowmeter measurements with the numerical simulation results or based on the reversal calculation, reducing damage to the reservoir, expanding the pressure drop distribution as much as possible. Use as a reference.

(Step 6)
In the later stages of mining, the dynamic liquid level is reduced after the liquid production of the coal seam is reduced, the stroke is reduced, the rate of descent of the dynamic liquid level is reduced, and the maximum gas production capacity is reached for each independent gas-containing system. , It is lowered to the top boundary of the semi-annular opening so that the coal seam is not exposed.

Embodiments of the present invention disclose preferred embodiments, but are not limited thereto. Those skilled in the art may modify or improve the disclosed embodiments based on the ideas of the present invention or based on the above embodiments, without departing from the technical ideas of the present invention. All improvements are included in the claims of the present application.

Claims (8)

Control pressure single pump mining equipment for independent gas containing system in multiple coal seams
It is equipped with an inner mantle tube (8) and an outer mantle tube (7).
The mantle tube (7) is fitted to the outside of the mantle tube (8).
The mantle tube (7) penetrates a plurality of independent gas-containing systems.
An oil supply pipe (6) is provided inside the inner body pipe (8), a soccer rod (5) is provided inside the oil supply pipe (6), and the bottom end of the soccer rod (5) and a tube pump. (13) is connected, a sand-sinking pipe (15) is provided at the bottom of the tube pump (13), and a phloem pipe (14) is provided above the sand-sinking pipe (15).
A first packer (11) and a second packer (12) are provided between the inner mantle tube (8) and the mantle tube (7), and the first packer (11) is the lowermost 2 Provided on the outside of the inner mantle (8) corresponding to the bottom end of each independent gas containing system except one independent gas containing system, the second packer (12) is the second independent from bottom to top. Provided on the outside of the inner trousers (8) corresponding to the bottom end of the gas containing system
The inner tube wall of the manometer (8) is provided with a pressure gauge manometer (1) and an annular current limiting valve manometer (2), and the bottom end of the manometer (1) is a pressure gauge (16). The pressure gauge (16) is provided at the bottom end of the inner wall of the manometer (8), and the bottom end of the annular current limiting valve electric pump (2) is the annular limiting current of each independent gas containing system. A control pressure single pump mining device for independent gas containing systems in multiple coal seams, characterized by being connected to a valve (9). The outer wall of the inner mantle tube (8) is provided with a plurality of semi-annular openings, and an annular current limiting valve (9) is attached to the outside of the semi-annular opening, and the height and diameter of the annular current limiting valve (9) are different. The controlled pressure single pump mining apparatus for an independent gas containing system in a plurality of coal seams according to claim 1, wherein the height and diameter of the semi-annular opening are larger than the height and diameter of the semi-annular opening. The annular current limiting valve (9) is composed of a current limiting valve (17) and a tractor (18), and the opening size of the annular current limiting valve (9) is the tractor (18) on the current limiting valve (17) side. The first or second aspect of the invention, wherein the annular current limiting valve electric pump (2) is connected to the tractor (18) through the wall of the inner mantle tube (8), which is controlled by the pull-in of the tractor. Control pressure single pump mining equipment for independent gas containing system in multiple coal seams. The mining device includes a gas flow meter (3) for measuring the gas production amount of the independent gas-containing system and a centralizer (4) for fixing the inner trouser tube, and the gas flow meter (3). The independent gas in the plurality of coal seams according to claim 1, wherein the centralizer (4) is provided between the inner pipe (8) and the outer pipe (7). Control pressure of containing system Single pump mining equipment. A gas production auxiliary passage (19) and an inner casing passage (20) are provided in the longitudinal direction of the first packer (11), and the inner trouser passage (20) is a central portion of the first packer (11). The gas production auxiliary passage (19) and the inner casing passage (20) are externally contacted, and the diameter of the gas production auxiliary passage (19) is smaller than that of the inner casing passage (20). (8) penetrates the inner mantle passage (20) and is fixed to the mantle tube (7), and the second packer (12) contains an independent gas-containing system at the bottom end and an independent gas-containing system adjacent thereto. The system is separated from the system, each independent gas-containing system is made into an individual independent structure, and an inner inner tube passage (20) for penetrating the inner inner tube (8) is provided in the longitudinal direction of the second packer (12). The control pressure single pump mining apparatus for an independent gas-containing system in a plurality of coal seams according to claim 1, wherein the control pressure is single pump. The mining device includes a plurality of gas production auxiliary pipes (10), the gas production auxiliary pipe (10) penetrates the gas production auxiliary passage (19), and the upper end portion of the gas production auxiliary pipe (10) and gas. The flow meter (3) is connected, the lower end is communicated with the corresponding independent gas-containing system, and the gas production auxiliary pipe (10) observes and adjusts the dynamic liquid level of each independent gas-containing system. The controlled pressure single pump mining apparatus for an independent gas containing system in a plurality of coal seams according to claim 1, wherein the device is used in The lower end of the gas production auxiliary pipe (10) is communicated with each independent gas-containing system except for the independent gas-containing system at the top end and the independent gas-containing system at the bottom end. A control pressure single pump mining device for an independent gas containing system in a plurality of coal seams according to 6. Control pressure single pump mining method for independent gas containing system in multiple coal seams
Based on the principle of osmosis mechanics, and by linking coal seam gas development experiments and numerical simulation technology, the steps to predict the transmission pattern of coal reservoir pressure and use it as the standard for the emission amount of the annular current limiting valve.
Based on the single coal layer gas content characteristic of the target region and the layer distribution property of the reservoir pressure, the coal seam group of the target region is partitioned into multiple independent gas containing systems, and the bottom side according to the partitioned independent gas containing system. A first packer is attached to the outside of the manometer corresponding to the bottom end of each independent gas containing system except for the two independent gas containing systems, and the bottom end of the second independent gas containing system from bottom to top. A second packer is attached to the outside of the inner manometer of the part, the gas production auxiliary passage in the first packer and the gas production auxiliary pipe are communicated, the pressure gauge electric wire and the pressure gauge are connected, and the pressure gauge is the inner manometer. A step that is fixed to the bottom of the inner wall of the pipe and seals the pressure gauge and the part that connects the pressure gauge and the pressure gauge electric gas.
Based on the partition results of the independent gas-containing systems and the reservoir characteristics of each gas-containing system, linked to the results of numerical simulations, depending on the height of the liquid column at the time of reaching the maximum gas production capacity of each independent gas-containing system. A semi-annular opening is opened and a stress receiving part is installed in advance, an annular current limiting valve is attached to the outside of the semi-annular opening, and the annular current limiting valve electric wire penetrates the tube wall of the inner mantle tube and is an annular current limiting valve. A step that is connected to the tractor and seals the connection between the annular current limiting valve and the annular current limiting valve electric wire,
The manometer, packer, and gas production auxiliary pipe to which the annular current limiting valve and pressure gauge are fixed are fixed to the design depth, and an independent space corresponding to the independent gas-containing system is provided between the manometer and the manometer. And the steps to form
Install the wellhead, start pumping, and during mining, plan the drainage volume of the annular current limiting valve based on the reservoir characteristics of each independent gas-containing system and the results of numerical simulations, and open each annular current limiting valve. Control the size, control the amount of water flowing into the pump port of each independent gas-containing system, read the measurements of the pressure gauge and gas flow meter, and confirm that the value of the pressure gauge decreases gently. This reduces damage to the reservoir, widens the pressure drop distribution as much as possible, and adjusts the flow of the annular current limiting valve by comparing the gas flowmeter measurements with the numerical simulation results or based on inversion calculations. The reference steps to be taken and
In the later stages of mining, the dynamic liquid level is reduced after the liquid production of the coal seam is reduced, the stroke is reduced, the rate of descent of the dynamic liquid level is reduced, and the maximum gas production capacity is reached for each independent gas-containing system. A controlled pressure single pump mining method for independent gas-containing systems in multiple coal seams, including a step down to the top boundary of a semi-annular opening so that the coal seams are not exposed.